Sub-Adult Chacma Baboon Skull, Papio ursinus, measuring approximately 6-1/4 inches long and 3-1/4 inches wide. Minor damage, some missing teeth - Review photos. The chacma baboon (Papio ursinus), also known as the Cape baboon, is, like all other baboons, from the Old World monkey family. It is one of the largest of all monkeys.